public class test3 {
    public static void main(String[] args) {
        double sum = 0.0;
        for (int i = 1; i <= 100; i++) {

            if (i % 2 == 0) {
                sum -= 1.0 / i;
            } else {
                sum += 1.0 / i;
            }
        }

        System.out.printf("The result is: %.10f\n", sum);
    }
}

